Simultaneous determination of atorvastatin and its metabolites in human plasma by UPLC-MS/MS

Abstract

A rapid, sensitive and selective ultra-performance liquid chromatography mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantification
of atorvastatin and all its as-yet-identified metabolites in human plasma. Atorvastatin, its metabolites, and the internal standard (IS) were isolated from human
plasma by liquid-liquid extraction with ethyl acetate and then separated on an Acquity UPLC HSS T3 column (3.0 mm * 100 mm, 1.8 um) using 0.05% (v/v) formic acid
in water/acetonitrile (25 : 75, v/v) as the mobile phase. Atorvastatin and all five metabolites were eluted within 4 min. Quantification was performed through positive
ion electrospray ionization (ESI). The responses of atorvastatin and its metabolites ortho-hydroxy atorvastatin, para-hydroxy atorvastatin, atorvastatin lactone, ortho-hydroxy
atorvastatin lactone, and para-hydroxy atorvastatin lactone were optimized at the m/z 559.4 - 440.1, m/z 575.4 - 466.2, m/z 575.5 - 440.5, m/z 541.3 - 448.3, m/z 557.3 - 448.3,
and m/z 557.3 448.3 transitions, respectively. The assay was validated in the linear range of 0.2-40 ng mL 1 for atorvastatin and its metabolites. The intra- and inter-day precision
variations were between 3.3% and 13.9%. The matrix effects of plasma were in the range of 102.7-105.5% for atorvastatin and 90.3-96.6% for atorvastatin lactone. This method was
successfully applied in clinical studies of atorvastatin in coronary artery disease patients.